Two marks (one above and one below the upper bulb) indicate a known volume. In use, liquid is drawn into the upper bulb by suction, then allowed to flow down through the capillary into the lower bulb. Above there is a bulb, with it is another bulb lower down on the other arm. In one arm of the U is a vertical section of precise narrow bore (the capillary). Another version is the Ubbelohde viscometer, which consists of a U-shaped glass tube held vertically in a controlled temperature bath. These devices are also known as glass capillary viscometers or Ostwald viscometers, named after Wilhelm Ostwald.
Viscosity testing verification#
We can supply instrument calibration verification to certified, traceable viscosity standards.Ostwald viscometers measure the viscosity of a fluid with a known density.
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Viscosity testing full#
Our laboratory a full complement of Brookfield viscometer instruments and accessories and can identify and perform the most appropriate tests for your needs. Brookfield viscosity can be fearsomely confusing due to a multitude of instrument types and accessories, many combinations of which can deliver widely varying viscosity measurements.
These machines employ, typically, a rotating spindle that dips into a beaker of the liquid to be tested. The term used to describe a viscosity value obtained with a Brookfield-type viscometer, rotational viscometer or similar-acting benchtop viscometers. Our high sophisticated testing equipment enables us to study viscosity as a function of static or dynamic temperature conditions. Our viscosity testing is performed under rigorous temperature controlled regimes. The degree of temperature dependence can be significant thus, it is critical to measure viscosity, under as close as possible conditions encountered in use, processing or storage. The majority of liquids show a decrease in viscosity with increasing temperature. A high value of zero-shear viscosity can help to immobilise suspended solids or emulsified liquid droplets, contributing significantly to physical stability. Far below the range typically attainable with a viscometer. Zero-shear viscosity is a plateau value obtained at very low shear. Performing viscosity testing under very low shear conditions also enables the measurement of zero-shear viscosity. We can clearly see the zero-shear viscosity plateaus. Zero-shear viscosity measurements Viscosity profiles across a range of shear rates. This is often the case in processes such as settling of suspensions, creaming of emulsions and draining and levelling of wet coatings. Viscosity/shear stress profiles are excellent for simulating altogether more gentle situations, where gravity, surface tension and capillary are the forces acting on the material. In this test, we apply a range of shear rates to the sample and measure viscosity throughout. Viscosity/shear rate or shear stress/shear rate profiles, often termed rheograms, are a great way of understanding product behaviour under “forced-flow” conditions such as in pumping, mixing or filling processes. Whether you are interested in the viscosity of your material for quality control, scale-up, research or stability assessments, we can work with you to identify an appropriate method as well as high quality data. We are happy to host a discussion of what the results mean in the context of your application of interest and can also provide viscosity training and consulting services. We provide a fully detailed results presentation with an explanation of the equipment, methods and techniques used. The resulting “flow curve” can help identify which viscosity values are relevant to your product or process. For shear-dependent products, it is very useful to measure viscosity across a range of shear conditions. Non-Newtonian fluids change their viscosity dependent upon the degree of shear applied. Most samples we receive include soft multi-phase materials, typically including suspensions, gels or emulsions, which tend to be non-Newtonian fluids. Viscosity Testing of non-Newtonian liquids
Send A Sample For Characterisation of Viscosity Every report includes ongoing Q&A support for interpretation or application of the results as part of our service offering. We have a wealth of experience testing a variety of complex materials. Whether you have a limited sample run, insufficient time to perform testing, or simply lack of equipment/expertise, we can help. On completion of testing you will receive a full report, including graphics, data tables and explanations. Our lab can perform viscosity measurements at defined temperatures in units of centiPoise (cP or “cps”) or milliPascal seconds (mPa.s) across a range of shear conditions. We are an expert viscosity testing lab providing a fast-turnaround viscosity characterisation service for liquids and semi-solids.
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